Microscopic blood tests are among the most diagnostically important and most frequently ordered tests in hospital and clinical environments worldwide. These tests are critically important for the screening of patients and the monitoring of treatment progress. Typically to perform a differential white blood cell count, a technician fixes and stains a blood slide. The red blood cells stain red and the white blood cells stain blue. The technician then mounts the slide in a manual microscope. At low power (usually a 10× objective) the technician must move the microscope up and down (Z direction) to focus the microscope on the slide and move the stage (X and Y directions) to find the areas of interest; note those areas; change the objective to a medium level (usually a 40-50× objective), commonly by turning a turret; refocus and reposition on the area of interest in order to locate and examine one hundred white blood cells; change the objective yet again to still higher power (usually a 100× objective) and immerse the slide and microscope objective into a blob of oil. The technician must then relocate the areas of interest to search for cells with the color, size and morphology of interest. All this focusing and stage movement is usually done manually and takes a significant amount of time. Typically, a technician spends five to six minutes per slide to do all these procedures. Positional and alignment errors can be introduced during these manipulations. For the highest power lens immersing of the lens and slide in a blob of oil dirties the whole system by capturing dust and other ambient materials. The object lens must be cleaned with care to avoid scratching the surface. The oil also tends to migrate to other microscope parts as well as the immediate work area. Counting of cells is a mindless, tedious task, given to distraction and human error. In sum, present day manual methods are time consuming, tedious, costly and can lead to errors. Clearly there is a need for the automation of these tests, particularly in a high volume clinical situation. Moreover, in order to keep the long term costs manageable, such an automated system needs to be robust and require minimal maintenance.
Several automated systems for analysis of stained blood cells have been developed to perform many of these tasks. Unfortunately, these automated systems are built around conventional microscopes, which are not designed for extended use in high volume applications. Also focus, X-Y transport and objective lens mechanisms designed for manual use exhibit backlash effects making difficult reliable and reproducible positioning, which is necessary for high quality imaging operations. Additionally, the adaptations of conventional microscopes do not address the problems of ambient jarring and temperature changes, which can translate to large positional errors.
In view of the problems in the deficiencies in the current automated microscope systems for blood analysis, there is a need for an improved configuration of an automated, precise, computer aided microscope that is rapid, inexpensive and robust.